---
id: "concept-share-of-model-d10"
type: "concept"
source_timestamps: ["§ The Rise of “Share of Model”"]
source_url: "https://hbr.org/2025/06/forget-what-you-know-about-seo-heres-how-to-optimize-your-brand-for-llms"
source_title: "Forget What You Know About Search. Optimize Your Brand for LLMs."
tags: ["metrics", "ai-awareness", "brand-tracking"]
related: ["concept-human-ai-awareness-gap", "concept-mention-rate", "framework-three-prong-ai-perception"]
definition: "A metric measuring how frequently, prominently, and favorably a brand is recommended by LLMs in response to consumer prompts."
sources: ["geo"]
sourceVaultSlug: "hbr-seg-geo"
originDay: 3
articleStem: "hbr-ext-10-optimize-brand-for-llms"
sourceUrl: "https://hbr.org/2025/06/forget-what-you-know-about-seo-heres-how-to-optimize-your-brand-for-llms"
sourceTitle: "Forget What You Know About Search. Optimize Your Brand for LLMs."
---
# Share of Model (SOM)

**Share of Model (SOM)** is the AI-era successor to the traditional visibility metrics **Share of Search (SOS)** and **Share of Voice (SOV)** (see [[prereq-traditional-seo-metrics]]). It measures *how often, how prominently, and how favorably* a brand is surfaced by Large Language Models (LLMs) in response to consumer prompts. Where SOS reflects human search *intent* and SOV reflects the raw *volume* of available content, SOM uniquely emulates an LLM's internal perceptions and recommendation logic.

A defining property of SOM is its **variability across models**. The same brand can post radically different scores on different platforms: a brand might hold a **24% SOM on Llama but less than 1% on Gemini**, reflecting how each model processes and weights brand information (see [[claim-llm-processing-styles-vary]]). The Italian detergent brand [[entity-chanteclair|Chanteclair]] illustrates this starkly — **19% SOM on Perplexity, entirely absent from Llama's recommendations**.

SOM is operationalized through the [[framework-three-prong-ai-perception|Three-Prong Lens for AI Brand Perception]] pioneered by [[entity-jellyfish-d3|Jellyfish]]: [[concept-mention-rate|mention rate]], the [[concept-human-ai-awareness-gap|Human-AI Awareness Gap]], and brand/category sentiment. The first practical step for any brand is to [[action-measure-som|measure SOM across multiple LLMs via scaled prompting]].

**Enrichment / external corroboration:** The extraction's definition is strongly corroborated by independent sources. Symphonic Digital defines SOM as "the number of mentions of a brand by one or multiple LLMs, as a proportion of total mentions of brands in the same category." Agile Brand Guide calls it "the AI-era counterpart to share of voice," measuring how often, prominently, and favorably a brand appears in LLM answers relative to competitors. TrySteakhouse frames it as measuring **entity salience** in LLM outputs, computing "citation probability" as (Total Mentions / Total Runs) × 100. A standalone platform, Shareofmodel.ai, now brands "Share of Model™" dashboards — evidence the term is congealing into a recognized category. **Caveat:** definitions are not yet standardized (mentions vs. citations vs. sentiment-weighting differ by vendor), and outputs vary run-to-run due to stochastic generation, so SOM should be treated as a *directional diagnostic and trend metric*, not yet a precise KPI on par with impression share (see [[question-som-volatility]]).


## Related across articles
- [[concept-share-of-model-d25]]
- [[concept-ai-recall-share]]
- [[concept-mention-rate]]


## Related across segments
- [[concept-share-of-model]]
- [[concept-ai-recall-share]]
- [[concept-share-of-model-d25]]